however the Tools/Options settings will only allow me to enter one User ID for both servers.

My ISP is 1smartisp.net, which will not allow me to use Yahoo's SMTP server. "Allow Authentication" is checked, and my Eudora version is 6 and OS is Windows 98SE.

The error message I get is:
Can't send. The server gives this reason: '550 not local host (domain) is not a gateway'.

The problem here I think is due to Eudora not allowing more than one User IDs. I tried Outlook Express, and was able to get the program to recognize both user ID's. But I don't want to use Outlook Express. Can anyone help me???

Ok. I made my mail.1smartisp.net account my "dominant" personality in SMTP & POP3 (so that I don't have to change the personality each time I send out a email) and my pop.mail.yahoo.com POP3 account a secondary personality (although it actually is my desired "primary" address to send - via From/Reply To - and receive messages). When I "Check Mail" in Eudora, it automatically checks all the personalities (dominant and secondaries) anyway. Thanks.